SERETIDE is used to help with asthma and Chronic obstructive disease in people who need regular treatment. Contains two medicines, salmeterol and fluticasone propionate: • Salmeterol is a long-acting bronchodilator. Bronchodilators help the airways in the lungs to stay open. This makes it easier for air to get in and out. The effects last for at least 12 hours. • Fluticasone propionate is a corticosteroid which reduces swelling and irritation in the lungs.